Noncorrosive antifreeze liquid



h w i ll Patented SEept. 5, 1939 UNITED STATES- NONCOBROSIVE mam moum Fred B. Whaley, Buflalo, N. Y., asslgnor to Carhide and carbonchcmioala Corporation, a corporation of New York No Drawing. Application January 2a, 1938,. Serial No. 187,432

18 Claims.

The invention relates to non-corrosive antifreeze liquids of the type containing an alcohol as the freezing point depressant. It is particularly concerned with inhibiting agents for such liquids adapted to suppress therein corrosive con- .ditions toward metals of a fluid cooling system.

Alcohols are now quite generally used in automotive engines to provide non-freezing cooling liquids, and many diilerent alcohols have been used for this purpose. Representative of these are methanol, ethanol, propanol or other monohydroxy alcohols, and the polyhydroxy compounds including ethylene and propylene glycol, diethylene glycol, or other glycols and their mixtures, and glycerol. The present invention is applicable to cooling fluids containing any of these alcohols as freezing point depressants, and an alcohol as referred to in the specification and claims is intended to include any of the monohydric or polyhydric compounds.

Alcohols are not inherently corrosive toward metals, but cooling fluids containing them are subjected to conditions in an automobile cooling system through which a corrosive action is often induced in the fluid. This may be due to a number of factors such as aeration during circulation of the water-diluted fluid, adventitious addition to the fluid of exhaust gases or other impurities, localized overheating, and other circumstances arising primarily from common faults of the usual cooling system. Itis, therefore, a known practice to employ corrosion inhiblti-ng materials with alcohols for use in antlfreeze solutions, to repress induced corrosive conditions and protect the metals of the cooling system. Many addition agents have been proposed for this purpose, but the protection afforded by prior inhibitors for all metals of the common cooling system, which includes iron, aluminum, copper, brass, and solder, has not been entirely satisfactory, and even where mixtures of a plurality of inhibitor compounds have been used, a deficiency in protection of one or more of the above metals is usually encountered;

It is an object of my invention to provide an improved corrosion inhibitorior alcohol cooling fluids, and an anti-freeze liquid in which induced corrosive conditions are repressed or prevented, to adequately protect all five metals of the cooling system.

I have found a group of compounds of excel lent inhibitor qualities, which by addition individually in very small quantities to an alcohol cooling fluid will repress induced corrosive action in such fluids under all normal operating conditions. These compounds may be broadly classed as aromatic nitro-carboxy derivatives, all members of which as a group appear to show a characteristic corrosion inhibiting action. Specific compounds of this class, which have proven by actual test to repress corrosion of iron, aluminum, copper, brass and solder, include such as ortho, meta and para nitrobenzoic acids, 3,5-dinitrobenzoic acid, 3-nitrophthallic acid, m-nitrohippuric acid, m-nitrocinnamic acid and p-nitrophenyl acetic acid. In each of these compounds the nitro group is attached directly to the benzene ring, but the carboxyl group may be on the ring or in a side chain, and the latter can be either saturated or unsaturated in character. These materials function as an inhibitor in neutral, alkaline and slightly acid solutions, and will maintain corrosion protection throughout the normal life of the cooling fluid. In methanol, ethylene glycol, and other mono and polyhydric alcohols, the presence of the inhibitor in amounts of about 0.05 to 1.0% by weight of the alcohol is sufllcient to provide excellent metal protection, and in all usual water dilutions as a cooling fluid the inhibitor remains effective.

As indicated, the aromatic nitro-carboxy compounds are efiective without further additions as a corrosion inhibitor, but other known inhibitor materials can be used in conjunction therewith if desired. Among the latter are certain oils, or agents for retarding leakage, compounds such as sodium nitrate and sodium nitrite for further specific aluminum and iron protection respectively, and basic materials which may aid in maintaining a reserve alkalinity in the cooling solution. These additional inhibitor components do not afiect the primary corrosion protection afforded by the nitro-carboxy compound, but the cooperative action of a plurality of inhibitors may be desirable for specific uses.

Representative formulae which have given especially good results in an ethylene glycol solution are shown in the following table, in which the amounts of various components are expressed in percentage by weight of the ethylene glycol:

parts sulfonated neats-foot oil, 90 parts mineral oil.

Many variations in the compositions shown will be evident, as will also the actual percentage of, the essential inhibitor and other components. In place of the straight acid compounds, salts of the aromatic nitro-carboxy derivatives may be equally efiective in inhibiting action, including such as the sodium and potassium salts, or organic derivatives such as the triethanolamine salt. Thesematerlals are intended to be included within the broad interpretation of aromatic nitrocarboxy compounds as referred to in the speciflcation and claims. Specific anti-leak ingredients, dyes for coloring the alcohol, and inhibitors tor other purposes may also be desirable, and many modifications are possible within the broader scope of this disclosure. The invention should not be limited other than as defined by the appended claims.

I claim:

1. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive. an aromatic nitrocarboxy compound, having a nitro group directly attached to the aromatic nucleus.

2. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive about 0.05% to 1.0% by weight of the alcohol of an aromatic nitro-carboxy compound, having a nitro group directly attached to the aromatic nucleus.

3. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive a nitro-carboxy compound derived from an acid of the group consisting of benzoic, phthallic, hippuric, cinnamic and phenylacetic acids, and having a nitro group directly attached to the aromatic nucleus.

4. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive about 0.05% to 1.0% by weight of the alcohol of a nitro-carboxy compound derived from an acid of the group consisting of benzoic, phthallic, hippuric, cinnamic and phenylacetic acids, and having a nitro group directly attached to the aromatic nucleus.

5. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive about 0.05% to 1.0% by weight of the alcohol of a nitrobenzoic acid.

6. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive about 0.05% to 1.0% by weight of the alcohol of 3,5-dinitrobenzoic acid.

'7. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive about 0.05% to 1.0% by weight oi. the alcohol of 3-nitrophthallic acid.

8. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor mixture containing an aromatic nitro-carboxy compound having a nitro group directly attached to the aromatic nucleus, an alkali metal nitrate, and a basic alkali metal compound. 4

9. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor mixtureconsisting of a nitrobenzoic acid, an alkali metal nitrate, an oil and a basic compound, of the group consisting of sodium carbonate and sodium hydroxide.

10. A non-corrosive anti-freeze liquid comprising an alcohol and an inhibitor mixture consisting of a nitrobenzoic acid, an alkali metal nitrate,'an alkali metal nitrite, and a basic compound, of the group consisting oi sodium carsodium nitrate, 1.5% oil, and 0.2% to 0.4% of a basic compound, of the group consisting of sodium carbonate and sodium hydroxide.

13. A non-corrosive anti-freeze liquid comprising ethylene glycol and an inhibitor mixture consisting in percentage by weight of the ethylene glycol of 0.3% p-nitrobenzoic acid, 0.3% sodium nitrite, 0.1% sodium nitrate, and 0.25% sodium carbonate.

14. Method of inhibiting corrosion of metals by an alcohol cooling fluid in contact therewith, which comprises contacting said fluid with the metal in the presence of an inhibitor containing as the essential corrosion preventive an aromatic nitro-carboxy compound having a nitro group directly attached to the aromatic nucleus, said compound being present in an amount about 0.05% to 1.0% by weight of the alcohol.

15. Method of inhibiting corrosion of metals by an alcohol cooling fluid in contact therewith, which comprises contacting said fluid with the metal in the presence of an inhibitor containing as the essential corrosion preventive a nitrocarboxy compound derived from an acid of the group consisting of benzoic, phthalllc, hippuric, cinnamic and phenylacetic acids, said inhibitor being present in an amount about 0.05% to 1.0% by weight of the alcohol.

16. Method of inhibiting corrosion of metals by an alcohol cooling fluid in contact therewith, which comprises contacting said fluid with the metal inthe presence of an inhibitor mixture consisting of a nitrobenzolc acid, sodium nitrate, oil, sodium carbonate, and sodium hydroxide.

1'7. Method of inhibiting corrosion of metals by an alcohol cooling fluid in contact therewith, which comprises contacting said fluid with the metal in the presence of an inhibitor mixture consisting of p-nitrobenzoic acid, sodium nitrite, sodium nitrate, and sodium carbonate.

18. Method of inhibiting corrosion of metals by an alcohol cooling fluid in contact therewith, which comprises contacting said fluid with the metal in the presence of an inhibitor mixture consisting of p-nitrobenzoic acid, sodium nitrate, and sodium carbonate.

FRED R. WHALEY. 

